Acoustical material and method of manufacturing same



. Patent d July-.1, 1930 lo Drawing.

Yu m'rao STATES PATENT OFFICE GEORGE D. KING- AND ROGER S'II'IT, CHICAGO, ILLINOIS, ASSIGNOBS TO STATES GYPSUM COHPAN Y, OF CHICAGO,

ILLINOIS, A CORPORATION 01 ILLINOIS acousrrcan mammal. am) mnon or muraorimme sun:

Application fled A ril 15,

This invention relates to sound absorbin or acoustical material and the method o these tile.

In the preparation of the sound absorbing composition and molded articles such as slabs, tile, etc., as described in the copending application of George D. King 'Serial No. 355,420 filed April 15, 1929, it is desirable to mix the ingredients of the composition in a correct manner so that the ingredients thereof will not so react as to defeat the purpose of the composition. The preparation of the slabs or tiles for ultimate use on the walls or ceil-' mgsof buildings, is also a salient feature of our nvention.

An object of this invention, therefore, is to prepare molding compositions of sound absorbing nature in such a wa that the ingredients of the composition wi 1 be properly compounded. v Another object of the invention is to so prepare the molded articles such as slabs, tile, etc., for use on walls and ceilin s of buildin that their maximum acoutica or sound a sorbing properties will be developed, and so mineral wool, known as that these articles will be pleasing to the eye and will be practical materials for construction and decoration.

A further object is to pre are the molded articles by an economical an practical method of manufacture also to improve sound absorbing articles and their methods ofmanufacture in other respects hereinafter, specified and claimed. y i

As a fibrous base for the improved composition, mineral wool is preferred because of its non-wiltin or water resistant character of the individua fibers, great connected porosity resultin in superior sound absorbin qualities, an also because of its fireproof an vermin-proof nature. Es cially good results were bad in'the use 0 a special form' ofanular mineral wool. This is mineral woo in the shape of highly porous little balls of rather irre ar shape, and of the size ofa pe'a or larger.

1m. Serial No. asaua granular wool is made by mechanically processing re lar wool and is procurable on the market, eing familiarly known as granulated mineral W001. W001 1 put into this form by any'process that gives wool of this character is suitable for the purpose of this composition. The granular wool is pourable and free-running, somewhat like cottonseed or corn kernels, whereas the re lar wool is matted or felted and is more "like cotton in character. The use of granular wool in the composition makes it easier to dry mix, and wet mixand easier to'mould into tile or appl as paint or plaster. It should be understoo however, that other fibrous .materials, especially if formed into granules, may be substitutedv as a base for the composition, such as wood or other cellulose fibers or other light weight material which is suitable. The other ingredients in ,this acoustical composition are 1. binder.

mechanically modified corn or. wheat flour such as is used in foundry cores; for example the artially dextrinized paste on the market. Suc a corn or wheat flour may be used in a dry mix of the ingredients for use as a palnt orbplaster, gauging water being added on the o Y I 5 J 2. An agent to give plasticity-to the com osition on mixing with water. Such p asticity enables rapld and easy mechanical formatlon of the tlle, etc., and more ractical a plication ofthe paint or plaster. or this araya' gum is preferred. If cooked starch is used in the composition it will largely serve this purpose, but it is preferable to use some of the gum gel even in such mixes, as the gum improves the plasticity and workability of the composition. Karaya m is similar to Forthis a-cooked, thick-boil- 'ing' starch gel is preferred. Another adhesive that may be used with good results is a tra canth gum in that it is capable of aba nt to give water resistance. For this I pref er to use an albuminous substance such as blood or animal glue, coupled with a salt such as copper sulfate. In a dry mixture of the ingredients for job use, the animal glue is preferable. A casein glue may be used. Some other salts ma 'be substituted for the cop er sulfate sue as lead acetate or mercuric c iloride. Aluminum sulfate, formaldehyde or potassium dichromate do not give good results.

Preferable but not essential ingredients are 4. A mineral filler to reduce the tendency of the binder to smolder on burning. Pyrophyllite is preferred because of its large bulk.

5. A preservative such as beta naphthol, alpha naphthylamine, etc. The copper sulfate also acts as a preservative.

6. Coloring matter such as raw sienna, iron oxide pigments, etc.

The preferred formula for the com osition as described in the aforementioned g application is as follows Globe pearl starch 5 lbs. Karaya gum 1% lbs. Raw sienna 10 ozs. Pyropliyllite 3 lbs. Beta naphthol oz. Copper sulfate 8 ozs.

Light blood albumin 1 lb. Granulated mineral wool 56 lbs. (4 cu. ft.)

Water sufiicient to give the desired plasticity.

The process of forming the tile or slabs from the composition is divided roughly into g1 Preparing the ingredients.

2 Wet mixing.

(3 Molding.

4 Drying.

5) Finishing.

If the modified corn flour is used instead of the cooked starch el and if a cold water soluble animal glue is used instead of the albumin, a dry mixture may be made of all the ingredients and therefore step (1), preparing the ingredients would consist only of drmixin them.

elow, owever, is given a referred procedure for plant molded tile, s abs, etc.

1. Preparing the ingredients (a) The cooked starch gel is made by brin mg to boiling the starch in 125lbs. of cold water, with preferably some stirring.

((lh) A fluid gel-like solution is made by ad ing to lbs. of cold water during fast agitation, the karaya gum, pyrophyllite and raw sienna.

(a) A solution is made of the cop r sulfate and beta naphthol in 5 lbs.- 0 warm water.

(d) The blood albumin is soaked i118 lbs. of cold water for several hours and then stirred into solution.

In making up the composition, solutions by simple molding, no

This operation is important and will govern to a lar e extent the character of tile, etc,

obtaine The liquid mixture, pre ared in (1), and the mineral wool are a dad toether in a suitable mixin vessel. This ma he a metal bowl or hal -c linder of en ficient size as to comforta 1y contain the batch, and fitted with blades of a nature to cut thru and artially turn the mass. The ipeed of mixing should be low (say 100 P. M.) so as to not unnecessaril break down the fibers or densify the mass. f gram ulated mineral wool is used, a shorter mix-' ing time is generally necessary than when the regular matted long fiber wool is used. If a tile of very uniform texture and color is desired the time of mixin should be increased. By a shorter mixing time a tile of more irregular and rougher structure, but greater sound absorption can be obtained.

' If granulated wool is used and if the mass is not mixed too long, the face of the resulting tile is composed of numerous soft s ts consisting of the balls of mineral wool w ich have not been materially penetrated by the binding agent, these balls being separated by a harder skeletonized structure containin a larger ercenta e of the binding material. The so spots, t e harder skeleton structure and the valleys or interstices between the granules have difief'ent sound absorbin qualities. Thus by regulating the degree 0 wet mixing, the sound absorption at the different pitches and the appearance of the tile can be largely controlled. If by mixing a short time only or by adding the coloring matter as a separate slurry, the coloring matter is mixed in to a degree so that only part of the granules of mineral wool will be penetrated by the color, the faoes'of the resulting tile, after finishing, will present a beautiful variegated or mottled appearance, of colored and uncolored areas. This surface resembles natural stone in appearance and yet is of a high degree of connected porosity and sound absorption.

' Molding As a result of the wet a plastic,

workable mass is obtained. This enables it to be converted into desirable shaor forms nee".-

The tile, etc, should be molded prefera 1y without pressing out any ap' reciable amount of the hquid orldensi 'ng e mass,

so' thatwhen the tile dries out, 1t will be light in weight and highly porous. While tile made-in this way have strength, tile of greater stren hand ter density may be made by mol wi I some ressure.

The plastic mass maybe molded into .any

suitable forms eitherbyihandor by machinery, such as by use of traveling molds, a master roll for levelin of, etc. Perforated metal late forms ma used to facilitate later rying, burlap eing used on the-bottom of 5 the molds for backing the plastic mass, In

place of the burlap, other open mesh fabric may beused. The mass is screeded off to the top ofthe form by hand screeds, master roll, etc. It is at times desirable to produce a tile having a rougher, more stone like appearance. Thism'ay be done by screeding with the edge of the screed and, instead of passing smoothly over the mass, dragging u some of the wool, resultin in rather large or valle s in the sur the tile mterior.

'The moldedslabs in the forms 'arefintro duced into suitable'driers such as are used for drying gypsum board or fiber wallboard. The drying should not be too fast, so asto prevent excessive shrinkage.- The tempera- .ture should not-be so hi h as to burn or high enou h to get full benefit from the .waterproo ng-action of the blood albumin and copper sulfate as heat seems to further complete the reaction between these two agents. A temperature of 200-250 F. is satisfactory. v y Y f 5.'F1'1 te'a]ting I .1 "After the slabs are dry, they are removed from the molds. The burlap may be stripped off or may be left on the slab as a permanent backin The slab is then cut into the desired finishe sizes with a saw, carborundum wheel ,or otherwise. One surface of the tile or slab is then bufied or ground by suitable means so that the outer surface of the tile is removed and the more porous interior, is exposed. This interior also presents a more pleasing texture and color, as the outer surface is marred by. some of the binder, waterproofer,

surface are a carborundum roll, a sanding belt, a planer, sand-blasting apparatus, etc. The opposite side of the tile may be bufled or ground slightly to level it up if desired. The tile or 'slab is then further shaped up into the design desired, beveling, etc. by means of a 'saw, carborundum wheel, or other- 05 wise. It is desirable to blow the dust accuace and extending into scorch the binders in the s ab, but should be etc. which has migrated to the surface during drying. Suitable means for removing the 7 that only part of the fibrous material is mulated b the sanding from the surface of Y The referred formula for molding into tile, 'sla s, etc., shows upontest of the tile of inch thickness, the following approximate sound absorption PltCl'l C2 G3 C4 05 C. 01 Absorption; .11 .30 .53 .70 .53 .53 percent The tile ma be attached to walls or ceilings by suitab e adhesives or b mechanical means. The surface of the app ied tile may be cleaned by refinishing the surface by sandpapering or other similar manner.

Treatment of walls and ceiliplgs of buildings with this composition not 0 y results in valuable acoustical correction but also furnishes in itself a pleasing decoration without further treatment. However, if desired, the tile may be surface treated with a stain etc. so that the pores of the tile will not be filled or covered.

We would state in conclusion that while the foregoing description represents a practical embodiment of our invention, we do not wish to limit ourselves precisely to these details since, manifestly, the same maybe considerably varied without departing from the spirit of the invention as defined in the pendedclaims.

1. The method of preparin acolored, por-f ous sound-absorbing materia which includes mixing integrally a colored pigment with a base of fibrous material, a binder and watera forming into the deslred shape,-drying, an

' removing the surface so asto expose the porous interior. v a

2. The method of forming n acoustical tile which includes mixing granular mineral wool, a binding agent, a waterproofin agent and a gel to form a plastic mass, moldingthe mass into articles of redetermined shape, drying, and mechanica ly finishing the surface of said article.

3. The method of reparing a sound absorbing material lwhich includes mixin a fibrous material and a binder forming mto the desired sha e, drying and removing the outer surface 0 the molded compositionso as to e se the interior.

4. e method of preparing a sound absorbing material which includes mixing a base of fibrous material with a binder and water so netrated by the binder, molding into articles, drying and finishin v 5. he method 0 lpreparing a sound absorbingmaterial whic includes mixing a base of granular, porous fibrous material with a Having thus described our invention, we claim as newand desire to secure by Letters binder, acoloring pigment and water so that I only part of the granules are penetrated by sorbing material which inclu the color, molding, drying, and finishing the surface of the product to form a variegated, mottled appearance.

6. The method of reparing a sound absorbing material whlch includes mixing a base of fibrous material with a binder and water, molding and screeding the surface so that the particles of the fibrous materialnear the. surface are pulled apart resulting in deep fissures in the surface, these fissures giving the finished tile a rough, natural stone-like appearance, and increased absorption area, drying and buffing off the surface. 7. The method of preparing a sound absorbing material which includes mixin a base of granular mineral wool with a inder, molding onto a fabric backing, drying, and trimming into the desired size.

8. The method of reparing a sound absorbin material which includes mixing a base 0 granular mineral wool with a binder and water, molding onto a fabric backing, drying, stripping off the fabric. and finishing.

9. The method of preparing a colored sound absorbing material which includes mixing integrally a coloring pigment with a base of mineral wool, a binder and water, forming into the desired shape, drying, and sanding off the surface.

10. The method of preparing a sound absorbing material which includes makin a mixture of fibrous material, water, a bin er, an albuminous substance and copper sulfate, molding this mixture, drying at a temperature high enou h to increase the efliciency of the waterproo g action of the albuminous substance and copper sulfate, and finishing ,the molded product.

11. The method of preparin a sound absorbing material which inclu es makin a fluid gel with starch, addin a solution 0 an albuminous substance, adding a solution of copper sulfate, molding the plastic mass, drying at approximately 200250 F., and removing the outer crust on the surface of the product. V I 12. The method of preparing a sound abbase of ranular fibrous material with a "binder an water, the mixing being carried on 4 in such a manner and to such a degree that the granules are not appreciably broken. up

* hat remain as separate entities so that the result ing finished product will be of a granular -appearance with valleys between some of the granules, moldin d ng and finishing.

13. The metho ofi reparing a sound absorbing material whic includes mixing mineral wool with water, a binder, a colorin pigment, and a waterproofer, the mixing 'ng carried on intensively so that the mass is uniform in color and texture and so that the wool ranular appearance, molding the mass, molding said plastic mass into slabs,

perforated plates being used as the bottoms o the molds so that drying will take place from both surfaces, drying, and subdividing said slabs b cuttin into sound absorbing tiles.

15. he met 0d of preparing acoustically absorbent tile which includes mixing a el binder, a waterproofing agent, and granu ar mineral wool to form a plastic mass, molding said mass into slabs, drying the slabs from both surfaces so as to prevent warping, subdividing said slabs by cutting into sound absorbing tile, and beveling the edges of said tile.

16. An acoustically absorbent tile composed of a composition molded in lastic form and containing mineral wool, a indin agent, a waterproofing agent, and a gel, sai tile having a sound absorbing, mechanically finished surface. i

17. The method of improving a sound absorbin porous, molded tile of fibrous material which includes removing the outer surface to expose the porous interior.

18. The method of preparing a sound absorbin material which includes mixing granu ated mineral wool with a gel-like mixture of cooked starch, karaya gum, yrophyllite, blood albumin, copper sul ate, beta naphthol, and raw sienna to form a plastic mass, moldin this plastic mass in forms to form molded articles of predetermined shape drying, cutting into desired sizes, removing the surface of the article to ex ose the porous interior, blowing dust out o the pores of the surface and beveling the edges of the article.

GEORGE D. KING. ROGER H. STITT.

s mixing a 'is thoroughly penetrated by the binder and 

